Oxidation of fats, vegetable oils, carotenoids and their biologically active derivatives, Vitamin A, and of essential oils and other flavorings results in degradation of their quality, and is deleterious to foodstuffs containing the oxidized products.
The art shows many methods of inhibiting lipid oxidation by adding fat-soluble antioxidants to the substrate. The art does not show the stabilization of fats by the use of undissolved ascorbic acid particles of any size. The lipid-soluble antioxidants include synthetics, such as BHA and BHT, or natural antioxidants, such as Labiatae extracts, and particularly rosemary and sage extracts. Fat-soluble esters of ascorbic acid are also used. The synthetic antioxidants are normally dissolved in the fat at levels not to exceed their permitted limits of 0.02%, whereas the natural antioxidants may be used at higher levels if their flavor level is not objectionable in the particular food or fat. Tocopherols, being naturally present in vegetable oils, may be added to animal fats to increase stability. In vegetable oils, they act as pro-oxidants at levels above about 2000 ppm.
Ascorbic acid, which is water soluble and fat insoluble, is a common additive to foods, where it serves to increase the Vitamin C content. In citrus beverages, it has been claimed to improve the flavor, and in pickle brines to improve the freshness. An important use is in curing brines in combination with nitrates and nitrites. In the curing of the meat, it reacts to form nitrous oxides, which in turn react with heme pigments to form the stable red colors of cured meats. It has been suggested that it reduces the formation of nitrosamines during the cooking of such meats.
Ascorbic acid has been used as an antioxidant from time immemorial. However, a search in U.S. Patent Office classes and subclasses, namely, Class 426, Subclasses 96, 98, 250, 534, 536, 540, 541, 547, 638, and 654; Class 260, Subclass 398.5; Class 252, Subclasses 314 and 363.5; Class 585, Subclass 351; and Class 514, Subclass 772, revealed no suggestion of the present invention. An update of the search in the U.S. Patent Office Class 426, Subclasses 72, 541, 544, 545, 546, 653, and 654; Class 424, Subclass 441; and Class 106, Subclass 263, and I.P.C. B 29C 49/00, extending over approximately the past year, and references cited in related applications, revealed only the following developments:
Ascorbic acid has been dissolved in an aqueous algae solution prior to spray drying, where it may reduce degradation due to the stresses of that operation.
It has been dissolved in aqueous solutions of tea extract, to extend the antioxidant power of the tea.
It is used as an acidulant, either in beverages per se, or incorporated into a gum matrix including polyvinyl acetate which releases it slowly upon chewing of the gum.
It is less preferred than glucose-glucose oxidase/catalase as an oxygen scavenger in aqueous phases of emulsions, and it is used in aqueous solutions of cosmetics.
Solid ascorbic acid is used in vitamin tablets. In some applications, it may be coated with a fatty acid, to permit adhesion of the particles to the surface of a dried food. It may be a component in a fat plug in baker's margarine, wherein the plug is designed to keep the components included in it from undesirably affecting the flavor of the margarine, but assisting the baker when incorporated in a dough.
Encapsulation of carotenoids in gelatin is an accepted method of reducing the rate at which they degrade. Similar retardation of oxidation is achieved by encapsulating fats or other substances in capsules, or coating the particles with an oxygen and light barrier such as an opaque sugar layer.
It has been dissolved in ethanol, which in turn is added to a mixture of lecithin and tocopherols, to form a transparent liquid upon removal of the ethanol. This ternary composition of ascorbic acid is suggested for use in highly unsaturated fats, in which it exhibits greater effectiveness than mixtures of tocopherol and lecithin alone.
In my copending U.S. application Ser. No., 07/544,248, now U.S. Pat. No. 5,084,293, ascorbic acid has been dissolved in a volatile solvent, such as methanol and water, and thence transferred into solution in a non-ionic emulsifier, with the solvent subsequently being removed. This forms an "activated ascorbic acid," which has powerful antioxidant properties in oleogenous media or with carotenoids and the like. Other of my copending applications show synergistic mixtures of natural antioxidants and certain emulsifiers as stabilizers for carotenoids.
Solid ascorbic acid has not been used or suggested for use as an antioxidant or stabilizer for fats or carotenoids, so far as can be ascertained, because it is insoluble in lipid media.